SEPTEMBER MEANS back to school for the country’s 55 million students. Too many students, though, will finish the month with two or three absences and, if that pattern continues, end up missing 10 percent of the school year. These are the students who probably will do poorly in school, who fail to complete courses and who are at greater risk of dropping out. We hope a new campaign that calls attention to the risks of chronic absenteeism will result in new efforts by states, schools and parents to get students to school and keep them there.

Forty national organizations have teamed with schools and community groups to call attention to the problem. The campaign includes research on the effects of absenteeism, public service and Twitter announcements, contests and other events. “We know that virtually every parent wants their child to be successful in school — but often parents and even teachers don’t realize how quickly absences can add up to academic risk,” said Hedy Chang, director of Attendance Works.

Studies show that 5 million to 7.5 million students miss nearly a month of schoolexcused and unexcused absences — every year. The effects, starting as early as pre-kindergarten, can be debilitating. In early grades, it means children are less likely to master reading by the end of third grade; by middle and high school, it means students are more likely to drop out.

Attendance has too long been viewed as an administrative or compliance matter, not as a way to boost student achievement. Students who live in poverty have some of the highest absenteeism rates and are the most at-risk academically. Moreover, school districts too often focus on truancy without tackling excused absences, which can be as big a problem.

New York City, where Mayor Michael Bloomberg created an interagency task force in 2010 to address these issues, is seen as a model of what’s possible. New York’s effort includes using data to identify children who are chronically absent, determining the barriers to attendance, engaging parents in solutions and rewarding results. The answer may be as simple as assuring parents that a school can deal with a child’s health issue or arranging safe transportation. Most impressive is New York’s program that matches chronically absent children with mentors who greet them at school or call home when they don’t show up to class.

Leslie A. Cornfeld, who chairs New York’s task force, told about a student who had had attendance problems but was now showing up every day. When asked why he had missed so much school, his answer was: “Nobody ever seemed to care if I was here or not before . . . when I am not in school now, they call my house right away.”